Some electronic devices require two different frequencies that are related to each other by approximately a 2:1 ratio. For example, a dual-band cellular telephone may operate at both 800 megahertz (MHz) and at 1900 MHz. Past means and methods of producing the two frequencies have suffered from several drawbacks. For example, the use of two different frequency generators adds to the size and to the cost of the product. Using one frequency generator coupled to a frequency-doubling circuit is a way around that limitation. However, past frequency doubling circuits suffer from a multitude of drawbacks.
Thus, it would be advantageous to produce a doubled frequency that does not require many external components and that has an output level substantially independent of the input level.